Aqueous polyurethane dispersions which are cured to form crosslinked paint films without the addition of curing agents such as polyfunctional isocyanates (at room temperature or slightly elevated temperature) or amino resins (conventionally at temperatures of over 100° C.) are already known from the literature. In EP-A 0 649 865 aqueous polyurethane dispersions are described which are functionalised by grafting with acrylic monomers containing ketone groups and which crosslink with dihydrazides such as adipic acid dihydrazide dissolved in the dispersion without addition of external curing agents. The drying behaviour of these dispersions is not yet satisfactory, however.
The object is to provide similar polyurethane dispersions which dry more quickly and exhibit an improved chemical resistance already after a short time.
The object is achieved by a self-crosslinking aqueous polyurethane dispersion containing polyurethane molecules having laterally or terminally bonded carbonyl groups.